Novel anti-notch3 antibodies and their use in the detection and diagnosis of disease

ABSTRACT

The present invention relates to novel antibodies that bind specifically to human Notch 3 and their use in the detection and/or diagnosis of Notch 3 related diseases, such as cancer. The present invention also includes nucleic acids encoding these novel antibodies, vectors and cell lines harboring the nucleic acids, and kits comprising the antibodies for use in the detection and diagnosis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 11/874,645, filed Oct. 18, 2007, which claims the benefit ofU.S. Provisional Application No. 60/852,861, filed Oct. 19, 2006. Thedisclosures of the foregoing applications are incorporated herein byreference in their entirety.

FIELD OF THE INVENTION

The present invention relates to novel anti-Notch 3 antibodies and theiruse in the detection of Notch 3 in a sample and/or diagnosis of aNotch-3 related disease or disorder.

BACKGROUND OF THE INVENTION

The Notch gene was first described in 1917 when a strain of the fruitfly Drosophila melanogaster was found to have notched wing blades(Morgan, Am Nat 51:513 (1917)). The gene was cloned some seventy yearslater and turned out to be a cell surface receptor playing a key role inthe development of many different cell types and tissues (Wharton etal., Cell 43:567-581 (1985)). Since then, the gene and its molecularmechanisms have been extensively studied. The generality of the Notchpathway manifests itself at different levels. At the genetic level, manymutations exist that affect the development of a very broad spectrum ofcell types in Drosophila.

The Notch signaling pathway was soon found to be an evolutionarilyconserved signaling mechanism from Drosophila to vertebrates and hasbeen found to be involved in many cellular processes, such asdifferentiation, cell fate decisions, maintenance of stem cells,proliferation, and apoptosis, in various cell types during and afterdevelopment (See review Artavanis, et al., Science 268:225 (1995)).Knockout mutations were found to be lethal in embryonic mice, consistentwith lymphoblastic leukemia (Ellisen, et al., Cell 66(4):649-661(1991)). The expression of mutant forms of Notch in developing Xenopusembryos interfere profoundly with normal development (Coffman, et al.,Cell 73 (1993)). In humans, there have been several genetic diseaseslinked to Notch mutations (Artavanis-Tsakonas, et al. Science284:770-776 (1999)).

Mammals possess four Notch proteins (designated Notch1 to 4) and fivecorresponding ligands (Delta-1, -3, and -4, and Jagged-1 and -2). Themammalian Notch gene encodes a ˜300 kd protein that is cleaved duringits transport to the cell surface and consequently exists as aheterodimer. The extracellular portion has many epidermal growth factor(EGF)-like repeats followed by three cysteine-rich Notch/Lin12 repeats(LN) (Wharton, et al., Cell 43:567 (1985); Kidd, et al., Mol Cell Biol6:3431 (1986); Kopczynski, et al., Genes Dev 2:1723 (1988); Yochem, etal., Nature 335:547 (1988)). The amino-terminal EGF-like repeatsparticipate in ligand binding, whereas the Lin 12 repeats preventsignaling in the absence of ligand. The signal induced by ligand bindingis transmitted to the nucleus by a process involving proteolyticcleavage of the receptor and nuclear translocation of the intracellulardomain (Notch-IC). After entering the nucleus, Notch-IC competes withinhibitory proteins and recruits coactivators, including mastermind-like(MAML) proteins, and acetyltransferases. The Notch-IC complex then bindsto a transcription factor RBP-J to convert it from a transcriptionalrepressor to an activator. The few transcriptional factors identified sofar vary in their nature and effects on the cell.

Cells in pathological states often express target antigens on theirsurface that are present in higher concentrations than on their normalcounterparts. The use of monoclonal antibodies to identify the presenceof these disease markers is attractive because of their highspecificities. Notch receptors have been linked to wide range ofdiseases, such as cancer, neurological disorders, and immune diseases,as reflected by its broad spectrum of activities in humans (Joutel, etal. Cell & Dev Biol 9:619 (1998); Nam, et al., Curr Opin Chem Biol 6:501(2002)). Many expression studies of Notch proteins in human tissues andcell lines have been reported. For example, increased levels of Notch3expression is found in many malignant tissues in humans. In leukemia,genetic and biochemical evidence show that Notch3 triggers multipleNF-kappaB activation pathways, which regulates distinct gene clustersinvolved in either cell differentitation or proliferation andleukemogenesis (Vacca, et al., EMBO J25:1000 (2006)). Notch3 is alsoexpressed in a subset of neuroblastoma cell lines and serves as a markerfor this type of tumor that has constitutional or tumor-specificmutations in the homeobox gene Phox2B, which controls part of thedifferentiation program of the sympathetic nervous system (van Limpt, etal., Cancer Lett 228:59 (2005)).

Notch3 is also found to be very important in the diagnosis of ovariancancer. Advanced-stage epithelial ovarian cancer has a poor prognosiswith a long-term survival in less than 30% of patients, whereas morethan 90% of patients can be cured by conventional therapy when thedisease is detected in stage I. No single marker is upregulated and shedin adequate amounts in early stages. Lu and colleagues screened the geneexpression of 41,441 known genes and expressed sequence tags betweenfive pools of normal ovarian surface epithelial cells and 42 epithelialovarian cancers of different stages, grades, and histotypes to identifytumor markers (Clin Cancer Res 10:3291 (2004)). The study found fourmarkers that were 3-fold upregulated and were able to distinguish alltumor samples from normal ovarian surface epithelial cells; one of thesegenes is Notch3. Other studies have also found that Notch3 expression isupregulated in a series of plasma cell neoplasm, including multiplemyeloma, plasma cell leukemia, and extramedullary plasmacytoma (Hedvat,et al., Br J Haematol 122:728 (2003); pancreatic cancer (Buchler, etal., Ann Surg 242:791 (2005)); and T cell acute lymphoblastic leukemias(T-ALL) (Bellavia, et al., Proc Natl Acad Sci USA 99:3788 (2002);Screpanti, et al., Trends Mol Med 9:30 (2003)).

Also, CADASIL (cerebral autosomal dominant arteriopathy with subcorticalinfarcts and leukoencephalopathy) causes a type of stroke and dementiawhose key features include recurrent subcortical ischaemic events andvascular dementia. CADASIL has been found to be associated with a mutantgene localized to chromosome 19 (Joutel, et al., Nature 383:707 (1996)).Joutel et al. identified mutations in CADASIL patients that causeserious disruption of the Notch 3 gene, indicating that Notch3 could bethe defective protein in CADASIL patients. Unfortunately, this highlyincapacitating and often lethal disease has remained largely undiagnosedor misdiagnosed as multiple sclerosis and Alzheimer's disease. Currentstudies would tend to demonstrate that it is a condition that is muchmore widespread than first thought. Efforts have been made to identifydiagnostic tools for the disease and develop a therapy.

An additional example of a Notch 3 related disease is familialhemiplegic migraine (FHM), the dominant autosomal form of migraine withaura, located in the same region of chromosome 19 as the Notch3 gene. Itshould be noted that more than 30% of patients suffering from CADASILalso suffer from migraine with aura. However, the latter is observed inonly about 5% of the population and this observation led to thediscovery of Notch3 gene involvement in the mechanism of this condition.Similarly, familial paroxytic ataxia has been linked to a gene locatedin the same region of chromosome 19 and implicating Notch3 in thiscondition. Other conditions and diseases that have been linked to Notch3include diabetes (Anastasi, et al., J Immunol 171:4504 (2003),rheumatoid arthritis (Yabe, et al., J Orthop Sci 10:589 (2005)), diseasestates in which vascular cell fate occur in vivo (Sweeney, et al., FASEBJ 18:1421 (2004)), and Alagille syndrome (Flynn, et al., J Pathol 204:55(2004)).

U.S. Pat. No. 5,786,158 describes diagnostic methods and compositionsfor the detection of malignancy or nervous system disorders based on thelevel of Notch proteins or nucleic acids. U.S. Application No.20020151487 describes a diagnostic test to determine the expressionlevels of Notch ligands, receptors, or other Notch signaling compoundsin cells.

Ongoing research studies are currently being pursued to identify otherdiseases and conditions linked to Notch3 expression. In view of thelarge number of human diseases associated with the Notch 3 signalingpathway, it is critical that new ways of detecting and diagnosing thesediseases be identified. The current invention provides novel anti-Notch3 antibodies useful for this unmet medical need.

SUMMARY OF THE INVENTION

The present invention provides novel antibodies and fragments thereofuseful in the detection and diagnosis of Notch-3 related diseases ordisorders.

One aspect of the invention relates to the nucleotide and amino acidsequences of these novel antibodies. Also included are vectors encodingsuch antibodies and cell lines harboring such vectors.

Another aspect of the invention relates to the use of these antibodiesin methods or assays for detecting Notch 3 activation or expression inpatients suspected of having a Notch-3 related disease or disorder. Suchdiseases or disorders may include, but not limited to, cerebralautosomal dominant arteriopathy with subcortical infarcts andleukoencephalopathy (CADASIL), T-cell acute lymphoblastic leukemia,lymphoma, Alagille syndrome, liver disease involving aberrantvasularization; diabetes, ovarian cancer, diseases involving vascularcell fate, rheumatoid arthritis, pancreatic cancer, plasma cellneoplasms (such as multiple myeloma, plasma cell leukemia, andextramedullary plasmacytoma), and neuroblastoma.

Another aspect of the invention relates to the screening of a patientsuspected of having a Notch3 related disease or condition to determineif such a patient would benefit from treatment with an anti-Notch 3antibody. Such detection includes both cell surface detection as well assoluble Notch3 found in the serum of said patient.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the amino acid sequence of human Notch 3. The EGF repeatregion extends from amino acid residue 43 to 1383 and is indicated by anunderline; the LIN12 domain extends from amino acid residue 1384 to 1503as indicated by bold italics; the Dimerization domain extends from aminoacid residue 1504 to 1640 as indicated by a box.

FIG. 2A depicts the heavy chain variable region sequence of anti-Notch 3monoclonal antibody mAb 255-71 (SEQ ID NO: 2).

FIG. 2B depicts the light chain (kappa) variable region sequence of mAb255A-71 (SEQ ID NO: 3).

FIG. 3A depicts the heavy chain variable region sequence of anti-Notch 3monoclonal antibody mAb 255A-77 (SEQ ID NO: 4).

FIG. 3B depicts the light chain (kappa) variable region sequence of mAb255A-77 (SEQ ID NO: 5).

FIG. 4A depicts the heavy chain variable region sequence of anti-Notch 3monoclonal antibody mAb 256A-13 (SEQ ID NO: 6).

FIG. 4B depicts the light chain (kappa) variable region sequence of mAb256A-13 (SEQ ID NO: 7).

DETAILED DESCRIPTION

This invention is not limited to the particular methodology, protocols,cell lines, vectors, or reagents described herein because they may vary.Further, the terminology used herein is for the purpose of describingparticular embodiments only and is not intended to limit the scope ofthe present invention. As used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural reference unless thecontext clearly dictates otherwise, e.g., reference to “a host cell”includes a plurality of such host cells. Unless defined otherwise, alltechnical and scientific terms and any acronyms used herein have thesame meanings as commonly understood by one of ordinary skill in the artin the field of the invention. Although any methods and materialssimilar or equivalent to those described herein can be used in thepractice of the present invention, the exemplary methods, devices, andmaterials are described herein.

All patents and publications mentioned herein are incorporated herein byreference to the extent allowed by law for the purpose of describing anddisclosing the proteins, enzymes, vectors, host cells, and methodologiesreported therein that might be used with the present invention. However,nothing herein is to be construed as an admission that the invention isnot entitled to antedate such disclosure by virtue.

DEFINITIONS

Terms used throughout this application are to be construed with ordinaryand typical meaning to those of ordinary skill in the art. However,Applicants desire that the following terms be given the particulardefinition as defined below.

The phrase “substantially identical” with respect to an antibody chainpolypeptide sequence may be construed as an antibody chain exhibiting atleast 70%, or 80%, or 90%, or 95% sequence identity to the referencepolypeptide sequence. The term with respect to a nucleic acid sequencemay be construed as a sequence of nucleotides exhibiting at least about85%, or 90%, or 95%, or 97% sequence identity to the reference nucleicacid sequence.

The term “identity” or “homology” shall be construed to mean thepercentage of amino acid residues in the candidate sequence that areidentical with the residue of a corresponding sequence to which it iscompared, after aligning the sequences and introducing gaps, ifnecessary to achieve the maximum percent identity for the entiresequence, and not considering any conservative substitutions as part ofthe sequence identity. Neither N- or C-terminal extensions norinsertions shall be construed as reducing identity or homology. Methodsand computer programs for the alignment are well known in the art.Sequence identity may be measured using sequence analysis software.

The term “antibody,” as used herein, refers to immunoglobulin moleculesand immunologically active portions of immunoglobulin molecules, i.e.,molecules that contain an antigen binding site that immunospecificallybinds an antigen. The immunoglobulin molecules of the invention can beof any type (e.g., IgG, IgE, IgM, IgD, IgA and IgY), class (e.g., IgG1,IgG2, IgG3, IgG4, IgA1 and IgA2) or subclass of immunoglobulin molecule.Moreover, the term “antibody” (Ab) or “monoclonal antibody” (mAb) ismeant to include intact molecules, as well as, antibody fragments (suchas, for example, Fab and F(ab′)₂ fragments) which are capable ofspecifically binding to a protein. Fab and F(ab′)₂ fragments lack the Fcfragment of intact antibody, clear more rapidly from the circulation ofthe animal or plant, and may have less non-specific tissue binding thanan intact antibody (Wahl, et al., J Nucl Med 24:316 (1983)).

As used herein, “anti-Notch3 antibody” means an antibody which binds tohuman Notch3 in such a manner so as to allow detection, diagnosis, orpredetermination of a disease associated with Notch 3 activation and/orexpression.

The term “variable” in the context of variable domain of antibodies,refers to the fact that certain portions of the variable domains differextensively in sequence among antibodies and are used in the binding andspecificity of each particular antibody for its particular target.However, the variability is not evenly distributed through the variabledomains of antibodies. It is concentrated in three segments calledcomplementarity determining regions (CDRs; i.e., CDR1, CDR2, and CDR3)also known as hypervariable regions both in the light chain and theheavy chain variable domains. The more highly conserved portions ofvariable domains are called the framework (FR). The variable domains ofnative heavy and light chains each comprise four FR regions, largely aadopting a β-sheet configuration, connected by three CDRs, which formloops connecting, and in some cases forming part of, the β-sheetstructure. The CDRs in each chain are held together in close proximityby the FR regions and, with the CDRs from the other chain, contribute tothe formation of the target binding site of antibodies (see Kabat, etal. Sequences of Proteins of Immunological Interest, National Instituteof Health, Bethesda, Md. (1987)). As used herein, numbering ofimmunoglobulin amino acid residues is done according to theimmunoglobulin amino acid residue numbering system of Kabat, et al.,unless otherwise indicated.

The term “antibody fragment” refers to a portion of a full-lengthantibody, generally the target binding or variable region. Examples ofantibody fragments include Fab, Fab′, F(ab′)₂ and Fv fragments. Thephrase “functional fragment or analog” of an antibody is a compoundhaving qualitative biological activity in common with a full-lengthantibody. For example, a functional fragment or analog of an anti-Notch3antibody is one which can bind to a Notch3 receptor in such a manner soas to prevent or substantially reduce the ability of such molecule fromhaving the ability to bind to its ligands. As used herein, “functionalfragment” with respect to antibodies, refers to Fv, F(ab) and F(ab′)₂fragments. An “Fv” fragment is the minimum antibody fragment whichcontains a complete target recognition and binding site. This regionconsists of a dimer of one heavy and one light chain variable domain ina tight, non-covalent association (V_(H)-V_(L) dimer). It is in thisconfiguration that the three CDRs of each variable domain interact todefine a target binding site on the surface of the V_(H)-V_(L) dimer.Collectively, the six CDRs confer target binding specificity to theantibody. However, even a single variable domain (or half of an Fvcomprising only three CDRs specific for a target) has the ability torecognize and bind target, although at a lower affinity than the entirebinding site.

The term “monoclonal antibody” as used herein refers to an antibodyobtained from a population of substantially homogeneous antibodies,i.e., the individual antibodies comprising the population are identicalexcept for possible naturally occurring mutations that may be present inminor amounts. Monoclonal antibodies herein specifically include“chimeric” antibodies (immunoglobulins) in which a portion of the heavyand/or light chain is identical with or homologous to correspondingsequences in antibodies derived from a particular species or belongingto a particular antibody class or subclass, which the remainder of thechain(s) is identical with or homologous to corresponding sequences inantibodies derived from another species or belonging to another antibodyclass or subclass, as well as fragments of such antibodies, so long asthey exhibit the desired biological activity (U.S. Pat. No. 4,816,567;and Morrison, et al., Proc Natl Acad Sci USA 81:6851 (1984)). Monoclonalantibodies are highly specific, being directed against a single targetsite. Furthermore, in contrast to conventional (polyclonal) antibodypreparations which typically include different antibodies directedagainst different determinants (epitopes), each monoclonal antibody isdirected against a single determinant on the target. In addition totheir specificity, monoclonal antibodies are advantageous in that theymay be synthesized by the hybridoma culture, uncontaminated by otherimmunoglobulins. The modifier “monoclonal” indicates the character ofthe antibody as being obtained from a substantially homogeneouspopulation of antibodies, and is not to be construed as requiringproduction of the antibody by any particular method. For example, themonoclonal antibodies for use with the present invention may be isolatedfrom phage antibody libraries using the well known techniques. Theparent monoclonal antibodies to be used in accordance with the presentinvention may be made by the hybridoma method first described by Kohler,et al., Nature 256:495 (1975), or may be made by recombinant methods.

The terms “cell,” “cell line,” and “cell culture” include progeny. It isalso understood that all progeny may not be precisely identical in DNAcontent, due to deliberate or inadvertent mutations. Variant progenythat have the same function or biological property, as screened for inthe originally transformed cell, are included. The “host cells” used inthe present invention generally are prokaryotic or eukaryotic hosts.

The term “vector” means a DNA construct containing a DNA sequence whichis operably linked to a suitable control sequence capable of effectingthe expression of the DNA in a suitable host. The vector may be aplasmid, a phage particle, or simply a potential genomic insert. Oncetransformed into a suitable host, the vector may replicate and functionindependently of the host genome, or may in some instances, integrateinto the genome itself. In the present specification, “plasmid” and“vector” are sometimes used interchangeably, as the plasmid is the mostcommonly used form of vector. However, the invention is intended toinclude such other forms of vectors which serve equivalent function asand which are, or become, known in the art.

The word “label” when used herein refers to a detectable compound orcomposition which can be conjugated directly or indirectly to a moleculeor protein, e.g., an antibody. The label may itself be detectable (e.g.,radioisotope labels or fluorescent labels) or, in the case of anenzymatic label, may catalyze chemical alteration of a substratecompound or composition which is detectable.

As used herein, “solid phase” means a non-aqueous matrix to which theantibody of the present invention can adhere. Example of solid phasesencompassed herein include those formed partially or entirely of glass(e.g. controlled pore glass), polysaccharides (e.g., agarose),polyacrylamides, polystyrene, polyvinyl alcohol, and silicones. Incertain embodiments, depending on the context, the solid phase cancomprise the well of an assay plate; in others it is a purificationcolumn (e.g. an affinity chromatography column).

As used herein, the term “Notch3-mediated disorder” means a condition ordisease which is characterized by the overexpression and/orhypersensitivity of the Notch3 receptor. Specifically it would beconstrued to include conditions associated with cerebral autosomaldominant arteriopathy with subcortical infarcts and leukoencephalopathy(CADASIL), T-cell acute lymphoblastic leukemia, lymphoma, Alagillesyndrome, liver disease involving aberrant vasularization; diabetes,ovarian cancer, diseases involving vascular cell fate, rheumatoidarthritis, pancreatic cancer, ovarian cancer, plasma cell neoplasms(such as multiple myeloma, plasma cell leukemia, and extramedullaryplasmacytoma), and neuroblastoma (Joutel, et al., Nature 383:673 (1996);Joutel, et al., Semin Cell Dev Biol 9:619 (1998); Nijjar, et al.,Hepatology 34:1184 (2001); Screpanti, et al., Trends Mol Med 9:30(2003); Anastasi, et al., J Immunol 171:4504 (2003); Lu, et al., ClinCancer Res 10:3291 (2004); Sweeney, et al., FASEB J 18:1421 (2004);Yabe, et al., J Orthop 10:589 (2005); Buchler, et al., Ann Surg 242:791(2005); Park, et al., Cancer Res 66:6312 (2006); Hedvat, et al., Br JHematol 122:728 (2003); van Limpt, et al., Cancer Lett 228:59 (2005)).

Immunogen

Recombinant Notch3 was used in immunizing mice to generate thehybridomas from which the novel antibodies of the present invention werefirst isolated. Recombinant Notch3 is commercially available from anumber of sources (see, e.g., R & D Systems, Minneapolis, Minn.,PeproTech, Inc., NJ, and Sanofi Bio-Industries, Inc., Tervose, Pa.).Alternatively, Notch 3 can be expressed from a gene or a cDNA encodingNotch3 by cloning into a plasmid or other expression vector andexpressing it in any of a number of expression systems according tomethods well known to those of skill in the art. Methods of cloning andexpressing nucleic acid sequences are well known (see, for example, U.S.Pat. Nos. 5,821,332 and 5,759,546). Because of the degeneracy of thegenetic code, a multitude of nucleotide sequences encoding Notch3polypeptides may be produced. One may vary the nucleotide sequence byselecting combinations based on possible codon choices. Thesecombinations are made in accordance with the standard triplet geneticcode as applied to the nucleotide sequence that codes for naturallyoccurring Notch3 polypeptide and all such variations are to beconsidered. Any one of these polypeptides may be used in theimmunization of an animal to generate antibodies that bind to Notch3.

The immunogen Notch3 polypeptide may, when beneficial, be expressed as afusion protein that has the Notch3 polypeptide attached to a fusionsegment. The fusion segment often aids in protein purification, e.g., bypermitting the fusion protein to be isolated and purified by affinitychromatography. Fusion proteins can be produced by culturing arecombinant cell transformed with a fusion nucleic acid sequence thatencodes a protein including the fusion segment attached to either thecarboxyl and/or amino terminal end of the protein. Fusion segments mayinclude, but are not limited to, immunoglobulin Fc regions,glutathione-S-transferase, β-galactosidase, a poly-histidine segmentcapable of binding to a divalent metal ion, and maltose binding protein.

Exemplary polypeptides comprise all or a portion of SEQ ID NO.1 orvariants or fragments thereof.

Antibody Generation

The antibodies of the present invention were generated by administeringan immunogen as described above to a host animal, in this case a mouse,to induce the production polyclonal antibodies specific for the antigen.The generation of these antibodies is described in Example I. In thehybridoma model, the host animal is immunized to elicit lymphocytes thatproduce or are capable of producing antibodies that will specificallybind to the protein used for immunization. Lymphocytes then are fusedwith myeloma cells using a suitable fusing agent, such as polyethyleneglycol, to form a hybridoma cell (Goding, Monoclonal Antibodies:Principles and Practice, Academic Press, pp. 59-103 (1986)).

Generally, in making antibody-producing hybridomas, either peripheralblood lymphocytes (“PBLs”) are used if cells of human origin aredesired, or spleen cells or lymph node cells are used if non-humanmammalian sources are desired. Immortalized cell lines are usuallytransformed mammalian cells, particularly myeloma cells of rodent,bovine or human origin. Typically, a rat or mouse myeloma cell line isemployed. The hybridoma cells may be cultured in a suitable culturemedium that preferably contains one or more substances that inhibit thegrowth or survival of the unfused, immortalized cells.

The culture medium in which hybridoma cells of the present inventionwere grown was assayed for production of monoclonal antibodies directedagainst Notch3. The binding specificity of monoclonal antibodiesproduced by hybridoma cells was determined by immunoprecipitation or byan in vitro binding assay, such as radioimmunoassay (RIA) orenzyme-linked immunoabsorbent assay (ELISA). Such techniques are knownin the art and within the skill of the artisan. The binding affinity ofthe monoclonal antibody to Notch3 can, for example, be determined by aScatchard analysis (Munson, et al., Anal Biochem 107:220 (1980)).

After hybridoma cells were identified that produce antibodies of thedesired specificity, affinity, and/or activity, the clones weresubcloned by limiting dilution procedures and grown by standard methods(Goding, Monoclonal Antibodies: Principles and Practice, Academic Press,pp. 59-103 (1986)). Suitable culture media for this purpose include, forexample, Dulbecco's Modified Eagle's Medium (D-MEM) or RPMI-1640 medium.In addition, the hybridoma cells may be grown in vivo as ascites tumorsin an animal.

The monoclonal antibodies secreted by the subclones were suitablyseparated or isolated from the culture medium by conventionalimmunoglobulin purification procedures such as, for example, proteinA-Sepharose, hydroxylaptite chromatography, gel exclusionchromatography, gel electrophoresis, dialysis, or affinitychromatography.

Identification of Anti-Notch 3 Antibodies

The present invention provides monoclonal antibodies that specificallybind Notch3 and allow the detection and/or diagnosis of Notch-3 relateddiseases and disorders. The antibodies of the present invention includethe antibodies designated 255A-71, 255A-77, and 256A-13 having thesequences of SEQ ID NOs 2-7. Candidate anti-Notch3 antibodies weretested by enzyme linked immunosorbent assay (ELISA), Westernimmunoblotting, or other immunochemical techniques. Assays performed tocharacterize the individual antibodies are described in the Examples 3and 4.

The antibodies may be human antigen-binding antibody fragments of thepresent invention and include, but are not limited to, Fab, Fab′ andF(ab′)₂, Fd, single-chain Fvs (scFv), single-chain antibodies,disulfide-linked Fvs (sdFv) and single-domain antibodies comprisingeither a VL or VH domain. Antigen-binding antibody fragments, includingsingle-chain antibodies, may comprise the variable region(s) alone or incombination with the entirety or a portion of the following: hingeregion, CH1, CH2, and CH3 domains. Also included in the invention areantigen-binding fragments comprising any combination of variableregion(s) with a hinge region, CH1, CH2, and CH3 domains.

Vectors and Host Cells

In another aspect, the present invention provides isolated nucleic acidsequences encoding an antibody variant as disclosed herein, vectorconstructs comprising a nucleotide sequence encoding the antibodies ofthe present invention, host cells comprising such a vector, andrecombinant techniques for the production of the antibody.

For recombinant production of the antibody, the nucleic acid encoding itis isolated and inserted into a replicable vector for further cloning(amplification of the DNA) or for expression. DNA encoding the antibodyis readily isolated and sequenced using conventional procedures (e.g.,by using oligonucleotide probes that are capable of binding specificallyto genes encoding the heavy and light chains of the antibody variant).Standard techniques for cloning and transformation may be used in thepreparation of cell lines expressing the antibodies of the presentinvention.

Vectors

Many vectors are available. The vector components generally include, butare not limited to, one or more of the following: a signal sequence, anorigin of replication, one or more marker genes, an enhancer element, apromoter, and a transcription termination sequence. Recombinantexpression vectors containing a nucleotide sequence encoding theantibodies of the present invention can be prepared using well knowntechniques. The expression vector may include a suitable transcriptionalor translational regulatory sequence such as those derived frommammalian, microbial, viral, or insect genes. Examples of regulatorysequences include transcriptional promoters, operators, enhancers, mRNAribosomal binding sites, and/or other appropriate sequences whichcontrol transcription and translation initiation and termination.Nucleotide sequences may be “operably linked” when the regulatorysequence functionally relates to the nucleotide sequence for theappropriate polypeptide. Thus, a promoter nucleotide sequence isoperably linked to, e.g., the antibody heavy chain sequence if thepromoter nucleotide sequence controls the transcription of theappropriate nucleotide sequence.

In addition, sequences encoding appropriate signal peptides that are notnaturally associated with antibody heavy and/or light chain sequencescan be incorporated into expression vectors. For example, a nucleotidesequence for a signal peptide (secretory leader) may be fused in-frameto the polypeptide sequence so that the antibody is secreted to theperiplasmic space or into the medium. A signal peptide that isfunctional in the intended host cells enhances extracellular secretionof the appropriate antibody. The signal peptide may be cleaved from thepolypeptide upon secretion of antibody from the cell. Examples of suchsecretory signals are well known and include, e.g., those described inU.S. Pat. Nos. 5,698,435; 5,698,417; and 6,204,023.

The vector may be a plasmid vector, a single or double-stranded phagevector, or a single or double-stranded RNA or DNA viral vector. Suchvectors may be introduced into cells as polynucleotides by well knowntechniques for introducing DNA and RNA into cells. The vectors, in thecase of phage and viral vectors also may be introduced into cells aspackaged or encapsulated virus by well known techniques for infectionand transduction. Viral vectors may be replication competent orreplication defective. In the latter case, viral propagation generallywill occur only in complementing host cells. Cell-free translationsystems may also be employed to produce the protein using RNAs derivedfrom the present DNA constructs. Such vectors may include the nucleotidesequence encoding the constant region of the antibody molecule (see,e.g., PCT Publications WO 86/05807 and WO 89/01036; and U.S. Pat. No.5,122,464) and the variable domain of the antibody may be cloned intosuch a vector for expression of the entire heavy or light chain.

Host Cells

The antibodies of the present invention can be expressed from anysuitable host cell. Examples of host cells useful in the presentinvention include prokaryotic, yeast, or higher eukaryotic cells andalso include but are not limited to microorganisms such as bacteria(e.g., E. coli, B. subtilis) transformed with recombinant bacteriophageDNA, plasmid DNA or cosmid DNA expression vectors containing antibodycoding sequences; yeast (e.g., Saccharomyces, Pichia) transformed withrecombinant yeast expression vectors containing antibody codingsequences; insect cell systems infected with recombinant virusexpression vectors (e.g., Baculovirus) containing antibody codingsequences; plant cell systems infected with recombinant virus expressionvectors (e.g., cauliflower mosaic virus, CaMV; tobacco mosaic virus,TMV) or transformed with recombinant plasmid expression vectors (e.g.,Ti plasmid) containing antibody coding sequences; or mammalian cellsystems (e.g., COS, CHO, BHK, 293, 3T3 cells) harboring recombinantexpression constructs containing promoters derived from the genome ofmammalian cells (e.g., metallothionein promoter) or from mammalianviruses (e.g., the adenovirus late promoter; the vaccinia virus 7.5Kpromoter).

Prokaryotes useful as host cells in the present invention include gramnegative or gram positive organisms such as E. coli, B. subtilis,Enterobacter, Erwinia, Klebsiella, Proteus, Salmonella, Serratia, andShigella, as well as Bacilli, Pseudomonas, and Streptomyces. Onepreferred E. coli cloning host is E. coli 294 (ATCC 31,446), althoughother strains such as E. coli B, E. coli X1776 (ATCC 31,537), and E.coli W3110 (ATCC 27,325) are suitable. These examples are illustrativerather than limiting.

Expression vectors for use in prokaryotic host cells generally compriseone or more phenotypic selectable marker genes. A phenotypic selectablemarker gene is, for example, a gene encoding a protein that confersantibiotic resistance or that supplies an autotrophic requirement.Examples of useful expression vectors for prokaryotic host cells includethose derived from commercially available plasmids such as the pKK223-3(Pharmacia Fine Chemicals, Uppsala, Sweden), pGEM1 (Promega Biotec,Madison, Wis., USA), and the pET (Novagen, Madison, Wis., USA) and pRSET(Invitrogen Corporation, Carlsbad, Calif., USA) series of vectors(Studier, J Mol Biol 219:37 (1991); Schoepfer, Gene 124:83 (1993)).Promoter sequences commonly used for recombinant prokaryotic host cellexpression vectors include T7, (Rosenberg, et al., Gene 56:125 (1987)),β-lactamase (penicillinase), lactose promoter system (Chang, et al.,Nature 275:615 (1978); Goeddel, et al., Nature 281:544 (1979)),tryptophan (trp) promoter system (Goeddel, et al., Nucl Acids Res 8:4057(1980)), and tac promoter (Sambrook, et al., Molecular Cloning, ALaboratory Manual, 2nd ed., Cold Spring Harbor Laboratory (1990)).

Yeasts or filamentous fungi useful in the present invention includethose from the genus Saccharomyces, Pichia, Actinomycetes,Kluyveromyces, Schizosaccharomyces, Candida, Trichoderma, Neurospora,and filamentous fungi such as Neurospora, Penicillium, Tolypocladium,and Aspergillus. Yeast vectors will often contain an origin ofreplication sequence from a 2μ yeast plasmid, an autonomouslyreplicating sequence (ARS), a promoter region, sequences forpolyadenylation, sequences for transcription termination, and aselectable marker gene. Suitable promoter sequences for yeast vectorsinclude, among others, promoters for metallothionein, 3-phosphoglyceratekinase (Hitzeman, et al., J Biol Chem 255:2073 (1980)) or otherglycolytic enzymes (Holland, et al., Biochem 17:4900 (1978)) such asenolase, glyceraldehyde-3-phosphate dehydrogenase, hexokinase, pyruvatedecarboxylase, phosphofructokinase, glucose-6-phosphate isomerase,3-phosphoglycerate mutase, pyruvate kinase, triosephosphate isomerase,phosphoglucose isomerase, and glucokinase. Other suitable vectors andpromoters for use in yeast expression are further described in Fleer, etal., Gene 107:285 (1991). Other suitable promoters and vectors for yeastand yeast transformation protocols are well known in the art. Yeasttransformation protocols are well known. One such protocol is describedby Hinnen, et al., Proc Natl Acad Sci 75:1929 (1978). The Hinnenprotocol selects for Trp⁺ transformants in a selective medium.

Mammalian or insect host cell culture systems may also be employed toexpress recombinant antibodies. In principle, any higher eukaryotic cellculture is workable, whether from vertebrate or invertebrate culture.Examples of invertebrate cells include plant and insect cells (Luckow,et al., Bio/Technology 6:47 (1988); Miller, et al., GeneticsEngineering, Setlow, et al., eds. Vol. 8, pp. 277-9, Plenam Publishing(1986); Mseda, et al., Nature 315:592 (1985)). For example, Baculovirussystems may be used for production of heterologous proteins. In aninsect system, Autographa califormica nuclear polyhedrosis virus (AcNPV)may be used as a vector to express foreign genes. The virus growsin—Spodoptera frugiperda cells. The antibody coding sequence may becloned individually into non-essential regions (for example thepolyhedrin gene) of the virus and placed under control of an AcNPVpromoter (for example the polyhedrin promoter). Other hosts that havebeen identified include Aedes, Drosophila melanogaster, and Bombyx mori.A variety of viral strains for transfection are publicly available,e.g., the L-1 variant of AcNPV and the Bm-5 strain of Bombyx mori NPV,and such viruses may be used as the virus herein according to thepresent invention, particularly for transfection of Spodopterafrugiperda cells. Moreover, plant cells cultures of cotton, corn,potato, soybean, petunia, tomato, and tobacco and also be utilized ashosts.

Vertebrate cells, and propagation of vertebrate cells, in culture(tissue culture) has become a routine procedure. See Tissue Culture,Kruse, et al., eds., Academic Press (1973). Examples of useful mammalianhost cell lines are monkey kidney; human embryonic kidney line; babyhamster kidney cells; Chinese hamster ovary cells/−DHFR (CHO, Urlaub, etal., Proc Natl Acad Sci USA 77:4216 (1980)); mouse sertoli cells; humancervical carcinoma cells (HELA); canine kidney cells; human lung cells;human liver cells; mouse mammary tumor; and NS0 cells.

Host cells are transformed with the above-described vectors for antibodyproduction and cultured in conventional nutrient media modified asappropriate for inducing promoters, transcriptional and translationalcontrol sequences, selecting transformants, or amplifying the genesencoding the desired sequences. Commonly used promoter sequences andenhancer sequences are derived from polyoma virus, Adenovirus 2, Simianvirus 40 (SV40), and human cytomegalovirus (CMV). DNA sequences derivedfrom the SV40 viral genome may be used to provide other genetic elementsfor expression of a structural gene sequence in a mammalian host cell,e.g., SV40 origin, early and late promoter, enhancer, splice, andpolyadenylation sites. Viral early and late promoters are particularlyuseful because both are easily obtained from a viral genome as afragment which may also contain a viral origin of replication. Exemplaryexpression vectors for use in mammalian host cells are commerciallyavailable.

The host cells used to produce the antibody of this invention may becultured in a variety of media. Commercially available media such asHam's F10 (Sigma), Minimal Essential Medium (MEM, Sigma), RPMI-1640(Sigma), and Dulbecco's Modified Eagle's Medium (DMEM, Sigma) aresuitable for culturing host cells. In addition, any of the mediadescribed in Ham, et al., Meth Enzymol 58:44 (1979), Barnes, et al.,Anal Biochem 102:255 (1980), and U.S. Pat. No. 4,767,704; 4,657,866;4,560,655; 5,122,469; 5,712,163; or 6,048,728 may be used as culturemedia for the host cells. Any of these media may be supplemented asnecessary with hormones and/or other growth factors (such as insulin,transferrin, or epidermal growth factor), salts (such as X-chlorides,where X is sodium, calcium, magnesium; and phosphates), buffers (such asHEPES), nucleotides (such as adenosine and thymidine), antibiotics (suchas GENTAMYCIN™ drug), trace elements (defined as inorganic compoundsusually present at final concentrations in the micromolar range), andglucose or an equivalent energy source. Any other necessary supplementsmay also be included at appropriate concentrations that would be knownto those skilled in the art. The culture conditions, such astemperature, pH, and the like, are those previously used with the hostcell selected for expression, and will be apparent to the ordinarilyskilled artisan.

Polynucleotides Encoding Antibodies

The invention further provides polynucleotides or nucleic acids, e.g.,DNA, comprising a nucleotide sequence encoding an antibody of theinvention and fragments thereof. Exemplary polynucleotides include thoseencoding antibody chains comprising one or more of the amino acidsequences described herein. The invention also encompassespolynucleotides that hybridize under stringent or lower stringencyhybridization conditions to polynucleotides that encode an antibody ofthe present invention.

The polynucleotides may be obtained, and the nucleotide sequence of thepolynucleotides determined, by any method known in the art. For example,a polynucleotide encoding the antibody may be assembled from chemicallysynthesized oligonucleotides (e.g., as described in Kutmeier, et al.,Bio/Techniques 17:242 (1994)), which, briefly, involves the synthesis ofoverlapping oligonucleotides containing portions of the sequenceencoding the antibody, annealing and ligating of those oligonucleotides,and then amplifying the ligated oligonucleotides by PCR.

In a specific embodiment, the amino acid sequence of the heavy and/orlight chain variable domains may be inspected to identify the sequencesof the CDRs by well known methods, e.g., by comparison to known aminoacid sequences of other heavy and light chain variable regions todetermine the regions of sequence hypervariability. Using routinerecombinant DNA techniques, one or more of the CDRs may be insertedwithin framework regions, e.g., into human framework regions to humanizea non-human antibody, as described supra. The framework regions may benaturally occurring or consensus framework regions, and preferably humanframework regions (see, e.g., Chothia, et al., J Mol Biol 278: 457(1998) for a listing of human framework regions). Preferably, thepolynucleotide generated by the combination of the framework regions andCDRs encodes an antibody that specifically binds a polypeptide of theinvention. Preferably, as discussed supra, one or more amino acidsubstitutions may be made within the framework regions, and, preferably,the amino acid substitutions improve binding of the antibody to itsantigen. Additionally, such methods may be used to make amino acidsubstitutions or deletions of one or more variable region cysteineresidues participating in an intrachain disulfide bond to generateantibody molecules lacking one or more intrachain disulfide bonds. Otheralterations to the polynucleotide are encompassed by the presentinvention and within the skill of the art.

In addition, techniques developed for the production of “chimericantibodies” (Morrison, et al., Proc Natl Acad Sci 81:851 (1984);Neuberger, et al., Nature 312:604 (1984); Takeda, et al., Nature 314:452(1985)) by splicing genes from a mouse antibody molecule of appropriateantigen specificity together with genes from a human antibody moleculeof appropriate biological activity can be used. As described supra, achimeric antibody is a molecule in which different portions are derivedfrom different animal species, such as those having a variable regionderived from a murine mAb and a human immunoglobulin constant region,e.g., humanized antibodies.

Alternatively, techniques described for the production of single chainantibodies (U.S. Pat. No. 4,946,778; Bird, Science 242:423 (1988);Huston, et al., Proc Natl Acad Sci USA 85:5879 (1988); and Ward, et al.,Nature 334:544 (1989)) can be adapted to produce single chainantibodies. Single chain antibodies are formed by linking the heavy andlight chain fragments of the Fv region via an amino acid bridge,resulting in a single chain polypeptide. Techniques for the assembly offunctional Fv fragments in E. coli may also be used (Skerra, et al.,Science 242:1038 (1988)).

Methods of Producing Anti-Notch3 Antibodies

The antibodies of the invention can be produced by any method known inthe art for the synthesis of antibodies, in particular, by chemicalsynthesis or preferably, by recombinant expression techniques.

Recombinant expression of an antibody of the invention, or fragment,derivative, or analog thereof, (e.g., a heavy or light chain of anantibody of the invention or a single chain antibody of the invention),requires construction of an expression vector containing apolynucleotide that encodes the antibody or a fragment of the antibody.Once a polynucleotide encoding an antibody molecule has been obtained,the vector for the production of the antibody may be produced byrecombinant DNA technology. An expression vector is constructedcontaining antibody coding sequences and appropriate transcriptional andtranslational control signals. These methods include, for example, invitro recombinant DNA techniques, synthetic techniques, and in vivogenetic recombination.

The expression vector is transferred to a host cell by conventionaltechniques and the transfected cells are then cultured by conventionaltechniques to produce an antibody of the invention. In one aspect of theinvention, vectors encoding both the heavy and light chains may beco-expressed in the host cell for expression of the entireimmunoglobulin molecule, as detailed below.

A variety of host-expression vector systems may be utilized to expressthe antibody molecules of the invention as described above. Suchhost-expression systems represent vehicles by which the coding sequencesof interest may be produced and subsequently purified, but alsorepresent cells which may, when transformed or transfected with theappropriate nucleotide coding sequences, express an antibody molecule ofthe invention in situ. Bacterial cells such as E. coli, and eukaryoticcells are commonly used for the expression of a recombinant antibodymolecule, especially for the expression of whole recombinant antibodymolecule. For example, mammalian cells such as NSO or CHO, inconjunction with a vector such as the major intermediate early genepromoter element from human cytomegalovirus, are an effective expressionsystem for antibodies (Foecking, et al., Gene 45:101 (1986); Cockett, etal., Bio/Technology 8:2 (1990)).

In addition, a host cell strain may be chosen which modulates theexpression of the inserted sequences, or modifies and processes the geneproduct in the specific fashion desired. Such modifications (e.g.,glycosylation) and processing (e.g., cleavage) of protein products maybe important for the function of the protein. Different host cells havecharacteristic and specific mechanisms for the post-translationalprocessing and modification of proteins and gene products. Appropriatecell lines or host systems can be chosen to ensure the correctmodification and processing of the foreign protein expressed. To thisend, eukaryotic host cells which possess the cellular machinery forproper processing of the primary transcript, glycosylation, andphosphorylation of the gene product may be used. Such mammalian hostcells include, but are not limited to, CHO, COS, 293, 3T3, or myelomacells.

For long-term, high-yield production of recombinant proteins, stableexpression is preferred. For example, cell lines which stably expressthe antibody molecule may be engineered. Rather than using expressionvectors which contain viral origins of replication, host cells can betransformed with DNA controlled by appropriate expression controlelements (e.g., promoter, enhancer, sequences, transcriptionterminators, polyadenylation sites, etc.), and a selectable marker.Following the introduction of the foreign DNA, engineered cells may beallowed to grow for one to two days in an enriched media, and then areswitched to a selective media. The selectable marker in the recombinantplasmid confers resistance to the selection and allows cells to stablyintegrate the plasmid into their chromosomes and grow to form foci whichin turn can be cloned and expanded into cell lines. This method mayadvantageously be used to engineer cell lines which express the antibodymolecule. Such engineered cell lines may be particularly useful inscreening and evaluation of compounds that interact directly orindirectly with the antibody molecule.

A number of selection systems may be used, including but not limited tothe herpes simplex virus thymidine kinase (Wigler, et al., Cell 11:223(1977)), hypoxanthine-guanine phosphoribosyltransferase (Szybalska, etal., Proc Natl Acad Sci USA 48:202 (1992)), and adeninephosphoribosyltransferase (Lowy, et al., Cell 22:817 (1980)) genes canbe employed in tk, hgprt or aprt-cells, respectively. Also,antimetabolite resistance can be used as the basis of selection for thefollowing genes: dhfr, which confers resistance to methotrexate (Wigler,et al., Proc Natl Acad Sci USA 77:357 (1980); O'Hare, et al., Proc NatlAcad Sci USA 78:1527 (1981)); gpt, which confers resistance tomycophenolic acid (Mulligan, et al., Proc Natl Acad Sci USA 78:2072(1981)); neo, which confers resistance to the aminoglycoside G-418 (Wu,et al., Biotherapy 3:87 (1991)); and hygro, which confers resistance tohygromycin (Santerre, et al., Gene 30:147 (1984)). Methods commonlyknown in the art of recombinant DNA technology may be routinely appliedto select the desired recombinant clone, and such methods are described,for example, in Ausubel, et al., eds., Current Protocols in MolecularBiology, John Wiley & Sons (1993); Kriegler, Gene Transfer andExpression, A Laboratory Manual, Stockton Press (1990); and in Chapters12 and 13, Dracopoli, et al., eds, Current Protocols in Human Genetics,John Wiley & Sons (1994); Colberre-Garapin, et al., J Mol Biol 150:1(1981), which are incorporated by reference herein in their entireties.

The expression levels of an antibody molecule can be increased by vectoramplification (for a review, see Bebbington, et al., “The use of vectorsbased on gene amplification for the expression of cloned genes inmammalian cells,” DNA Cloning, Vol. 3. Academic Press (1987)). When amarker in the vector system expressing antibody is amplifiable, increasein the level of inhibitor present in culture of host cell will increasethe number of copies of the marker gene. Since the amplified region isassociated with the antibody gene, production of the antibody will alsoincrease (Crouse, et al., Mol Cell Biol 3:257 (1983)).

The host cell may be co-transfected with two expression vectors of theinvention, the first vector encoding a heavy chain derived polypeptideand the second vector encoding a light chain derived polypeptide. Thetwo vectors may contain identical selectable markers which enable equalexpression of heavy and light chain polypeptides. Alternatively, asingle vector may be used which encodes, and is capable of expressing,both heavy and light chain polypeptides. In such situations, it may bepreferable to place the light chain before the heavy chain to avoid anexcess of free heavy chain (Proudfoot, Nature 322:52 (1986); Kohler,Proc Natl Acad Sci USA 77:2197 (1980)). The coding sequences for theheavy and light chains may comprise cDNA or genomic DNA.

Once an antibody molecule of the invention has been produced by ananimal, chemically synthesized, or recombinantly expressed, it may bepurified by any method known in the art for purification of animmunoglobulin molecule, for example, by chromatography (e.g., ionexchange, affinity, particularly by affinity for the specific antigenafter Protein A, and size-exclusion chromatography), centrifugation,differential solubility, or by any other standard technique for thepurification of proteins. In addition, the antibodies of the presentinvention or fragments thereof can be fused to heterologous polypeptidesequences described herein or otherwise known in the art, to facilitatepurification.

The present invention encompasses antibodies recombinantly fused orchemically conjugated (including both covalently and non-covalentlyconjugations) to a polypeptide. Fused or conjugated antibodies of thepresent invention may be used for ease in purification. See e.g., PCTpublication WO 93/21232; EP 439,095; Naramura, et al., Immunol Lett39:91 (1994); U.S. Pat. No. 5,474,981; Gillies, et al., Proc Natl AcadSci USA 89:1428 (1992); Fell, et al., J Immunol 146:2446 (1991), whichare incorporated by reference in their entireties.

Moreover, the antibodies or fragments thereof of the present inventioncan be fused to marker sequences, such as a peptide to facilitatepurification. In preferred embodiments, the marker amino acid sequenceis a hexa-histidine peptide, such as the tag provided in a pQE vector(QIAGEN, Inc., 9259 Eton Avenue, Chatsworth, Calif., 91311), amongothers, many of which are commercially available. As described in Gentz,et al., Proc Natl Acad Sci USA 86:821 (1989), for instance,hexa-histidine provides for convenient purification of the fusionprotein. Other peptide tags useful for purification include, but are notlimited to, the “HA” tag, which corresponds to an epitope derived fromthe influenza hemagglutinin protein (Wilson, et al., Cell 37:767 (1984))and the “flag” tag.

Antibody Purification

When using recombinant techniques, the antibodies of the presentinvention can be produced intracellularly, in the periplasmic space, ordirectly secreted into the medium. If the antibodies are producedintracellularly, as a first step, the particulate debris, either hostcells or lysed fragments, may be removed, for example, by centrifugationor ultrafiltration. Carter, et al., Bio/Technology 10:163 (1992)describe a procedure for isolating antibodies which are secreted to theperiplasmic space of E. coli. Briefly, cell paste is thawed in thepresence of sodium acetate (pH 3.5), EDTA, andphenylmethylsulfonylfluoride (PMSF) over about 30 minutes. Cell debriscan be removed by centrifugation. When the antibodies are secreted intothe medium, supernatants from such expression systems are generallyconcentrated using a commercially available protein concentrationfilter, for example, an Amicon or Millipore Pellicon ultrafiltrationunit. A protease inhibitor such as PMSF may be included in any of theforegoing steps to inhibit proteolysis and antibiotics may be includedto prevent the growth of adventitious contaminants.

The antibody composition prepared from the cells can be purified using,for example, hydroxylapatite chromatography, gel electrophoresis,dialysis, and affinity chromatography, with affinity chromatographybeing the preferred purification technique. The suitability of protein Aas an affinity ligand depends on the species and isotype of anyimmunoglobulin Fc domain that is present in the antibody variant.Protein A can be used to purify antibodies that are based on human IgG1,IgG2 or IgG4 heavy chains (Lindmark, et al., J Immunol Meth 62:1(1983)). Protein G is recommended for all mouse isotypes and for humanIgG3 (Guss, et al., EMBO J. 5:1567 (1986)). The matrix to which theaffinity ligand is attached is most often agarose, but other matricesare available. Mechanically stable matrices such as controlled poreglass or poly(styrenedivinyl)benzene allow for faster flow rates andshorter processing times than can be achieved with agarose. Where theantibody comprises a CH3 domain, the Bakerbond ABXTM resin (J. T. Baker;Phillipsburg, N.J.) is useful for purification. Other techniques forprotein purification such as fractionation on an ion-exchange column,ethanol precipitation, Reverse Phase HPLC, chromatography on silica,chromatography on heparin SEPHAROSE™ chromatography on an anion orcation exchange resin (such as a polyaspartic acid column),chromatofocusing, SDS-PAGE, and ammonium sulfate precipitation are alsoavailable depending on the antibody to be recovered.

Following any preliminary purification step(s), the mixture comprisingthe antibody of interest and contaminants may be subjected to low pHhydrophobic interaction chromatography using an elution buffer at a pHbetween about 2.5-4.5, preferably performed at low salt concentrations(e.g., from about 0-0.25M salt).

Diagnostic Uses for Anti-Notch3 Antibodies

The antibodies of the invention include derivatives that are modified,i.e., by the covalent attachment of any type of molecule to theantibody, such that covalent attachment does not interfere with bindingto Notch3. For example, but not by way of limitation, the antibodyderivatives include antibodies that have been modified, e.g., bybiotinylation, HRP, or any other detectable moiety.

Antibodies of the present invention may be used, for example, but notlimited to, to purify or detect Notch3, including both in vitro and invivo diagnostic methods. For example, the antibodies have use inimmunoassays for qualitatively and quantitatively measuring levels ofNotch3 in biological samples. See, e.g., Harlow, et al., Antibodies: ALaboratory Manual, Cold Spring Harbor Laboratory Press, 2nd ed. (1988),which is incorporated by reference herein in its entirety.

As discussed in more detail below, the antibodies of the presentinvention may be used either alone or in combination with othercompositions. The antibodies may further be recombinantly fused to aheterologous polypeptide at the N- or C-terminus or chemicallyconjugated (including covalently and non-covalently conjugations) topolypeptides or other compositions. For example, antibodies of thepresent invention may be recombinantly fused or conjugated to moleculesuseful as labels in detection assays.

The present invention further encompasses antibodies or fragmentsthereof conjugated to a diagnostic agent. The antibodies can be useddiagnostically, for example, to detect expression of a target ofinterest in specific cells, tissues, or serum; or to monitor thedevelopment or progression of an immunologic response as part of aclinical testing procedure to, e.g., determine the efficacy of a giventreatment regimen. Detection can be facilitated by coupling the antibodyto a detectable substance. Examples of detectable substances includevarious enzymes, prosthetic groups, fluorescent materials, luminescentmaterials, bioluminescent materials, radioactive materials, positronemitting metals using various positron emission tomographies, andnonradioactive paramagnetic metal ions. The detectable substance may becoupled or conjugated either directly to the antibody (or fragmentthereof) or indirectly, through an intermediate (such as, for example, alinker known in the art) using techniques known in the art. Examples offluorescent labels include rare earth chelates (europium chelates) andfluorescein and its derivatives, rhodamine and its derivatives, dansyl,Lissamine, phycoerythrin and Texas Red. The fluorescent labels can beconjugated to the antibody using the techniques disclosed in CurrentProtocols in Immunology, Volumes 1 and 2, Coligen, et al., Ed.Wiley-Interscience, New York (1991), for example. Fluorescence can bequantified using a fluorimeter. Various enzyme-substrate labels areavailable and U.S. Pat. No. 4,275,149 provides a review of some ofthese. The enzyme generally catalyzes a chemical alteration of thechromogenic substrate which can be measured using various techniques.For example, the enzyme may catalyze a color change in a substrate,which can be measured spectrophotometrically. Alternatively, the enzymemay alter the fluorescence or chemiluminescence of the substrate, whichmay be quantified using a fluorimeter. The chemiluminescent substratebecomes electronically excited by a chemical reaction and may then emitlight which can be measured (using a chemiluminometer, for example) ordonates energy to a fluorescent acceptor. Examples of enzymatic labelsinclude luciferases (e.g., firefly luciferase and bacterial luciferase;U.S. Pat. No. 4,737,456), luciferin, 2,3-dihydrophthalazinediones,malate dehydrogenase, urease, peroxidase such as horseradish peroxidase(HRPO), alkaline phosphatase, beta.-galactosidase, glucoamylase,lysozyme, saccharide oxidases (e.g., glucose oxidase, galactose oxidase,and glucose-6-phosphate dehydrogenase), heterocyclic oxidases (such asuricase and xanthine oxidase), lactoperoxidase, microperoxidase, and thelike. Techniques for conjugating enzymes to antibodies are described inO'Sullivan, et al., “Methods for the Preparation of Enzyme-AntibodyConjugates for Use in Enzyme Immunoassay,” in Methods in Enzymology,Langone, et al., eds. pp. 147-66, Academic Press (1981). See, forexample, U.S. Pat. No. 4,741,900 for metal ions which can be conjugatedto antibodies for use as diagnostics according to the present invention.Examples of suitable enzymes include horseradish peroxidase, alkalinephosphatase, beta-galactosidase, or acetylcholinesterase; examples ofsuitable prosthetic group complexes include streptavidin/biotin andavidin/biotin; examples of suitable fluorescent materials includeumbelliferone, fluorescein, fluorescein isothiocyanate, rhodamine,dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin; anexample of a luminescent material includes luminol; examples ofbioluminescent materials include luciferase, luciferin, and aequorin;and examples of suitable radioactive material include ¹²⁵I, ¹³¹I, ¹¹¹Inor ⁹⁹Tc.

Sometimes, the label is indirectly conjugated with the antibody. Theskilled artisan will be aware of various techniques for achieving this.For example, the antibody can be conjugated with biotin and any of thethree broad categories of labels mentioned above can be conjugated withavidin, or vice versa. Biotin binds selectively to avidin and thus, thelabel can be conjugated with the antibody in this indirect manner.Alternatively, to achieve indirect conjugation of the label with theantibody, the antibody is conjugated with a small hapten (e.g.,digloxin) and one of the different types of labels mentioned above isconjugated with an anti-hapten antibody (e.g., anti-digloxin antibody).Thus, indirect conjugation of the label with the antibody variant can beachieved.

In another embodiment of the invention, the antibody need not belabeled, and the presence thereof can be detected using a labeledantibody which binds to the antibody.

The antibodies of the present invention may be employed in any knownassay method, such as competitive binding assays, direct and indirectsandwich assays, and immunoprecipitation assays. See Zola, MonoclonalAntibodies: A Manual of Techniques, pp. 147-158, CRC Press (1987).

Competitive binding assays rely on the ability of a labeled standard tocompete with the test sample for binding with a limited amount ofantibody variant. The amount of target in the test sample is inverselyproportional to the amount of standard that becomes bound to theantibodies. To facilitate determining the amount of standard thatbecomes bound, the antibodies generally are insolubilized before orafter the competition. As a result, the standard and test sample thatare bound to the antibodies may conveniently be separated from thestandard and test sample which remain unbound.

Sandwich assays involve the use of two antibodies, each capable ofbinding to a different immunogenic portion, or epitope, or the proteinto be detected. In a sandwich assay, the test sample to be analyzed isbound by a first antibody which is immobilized on a solid support, andthereafter a second antibody binds to the test sample, thus forming aninsoluble three-part complex. See e.g., U.S. Pat. No. 4,376,110. Thesecond antibody may itself be labeled with a detectable moiety (directsandwich assays) or may be measured using an anti-immunoglobulinantibody that is labeled with a detectable moiety (indirect sandwichassay). For example, one type of sandwich assay is an ELISA assay, inwhich case the detectable moiety is an enzyme.

Antibodies may be attached to solid supports, which are particularlyuseful for detection of Notch 3 in a sample. These antibodies are alsouseful for affinity purification agents, in immunoassays or purificationof the target antigen. Such solid supports include, but are not limitedto, glass, cellulose, polyacrylamide, nylon, polystyrene, polyvinylchloride or polypropylene. These may take the form of a microtiterplate, a slide, a bead, a tube, resins such as SEPHADEX™ resin, filterpaper or any other support useful in the attachment of an antibody forsuch purposes. In this process, the antibodies are immobilized on asolid support using methods well known in the art. The immobilizedantibodies are contacted with a sample containing the target to bedetected or purified, and thereafter the support is washed with asuitable solvent that will remove substantially all the material in thesample except the target, which is bound to the immobilized antibodies.The antibodies can then be detected by typical means such ascolorimetric assays, chemiluminscent assays, or by radioactive labeling.If the antibody is being used for purification, the support may bewashed with another suitable solvent, such as glycine buffer, that willrelease the target from the antibodies.

Labeled antibodies, and derivatives and analogs thereof, whichspecifically bind to Notch3 can be used for diagnostic purposes todetect, diagnose, or monitor diseases, disorders, and/or conditionsassociated with the aberrant expression and/or activity of Notch3. Theinvention provides for the detection of aberrant expression of Notch3,comprising (a) assaying the expression of Notch3 in cells or body fluidof an individual using one or more antibodies of the present inventionspecific to Notch3 and (b) comparing the level of gene expression with astandard gene expression level, whereby an increase or decrease in theassayed Notch3 expression level compared to the standard expressionlevel is indicative of aberrant expression.

Antibodies may be used for detecting the presence and/or levels ofNotch3 in a sample, e.g., a bodily fluid or tissue sample. The detectingmethod may comprise contacting the sample with a Notch3 antibody anddetermining the amount of antibody that is bound to the sample. Forimmunohistochemistry, the sample may be fresh or frozen or may beembedded in paraffin and fixed with a preservative such as formalin, forexample.

The invention provides a diagnostic assay for diagnosing a disorder,comprising (a) assaying the expression of Notch3 in cells or body fluidof an individual using one or more antibodies of the present inventionand (b) comparing the level of Notch3 protein expression with a standardprotein expression level, whereby an increase or decrease in the assayedexpression level compared to the standard expression level is indicativeof a particular disorder.

Antibodies of the invention can be used to assay protein levels in abiological sample using classical immunohistological methods known tothose of skill in the art (e.g., see Jalkanen, et al., J Cell Biol101:976 (1985); Jalkanen, et al., J Cell Biol 105:3087 (1987)). Theantibodies may also be used for in vivo diagnostic assays. Otherantibody-based methods useful for detecting protein expression includeimmunoassays, such as the enzyme linked immunosorbent assay (ELISA) andthe radioimmunoassay (RIA). Suitable antibody assay labels are known inthe art and include enzyme labels, such as, glucose oxidase;radioisotopes, such as iodine (¹³¹I, ¹²⁵I, ¹²¹I), carbon (¹⁴C), sulfur(³⁵S), tritium (³H), indium (¹¹²In, ¹¹¹In), and technetium (⁹⁹Tc);luminescent labels, such as luminol; and fluorescent labels, such asfluorescein, rhodamine, and biotin. Radioisotope-bound isotopes may belocalized using immunoscintiography. The antibody can be labeled withthe radioisotope suing the techniques described in Current Protocols inImmunology, Volumes 1 and 2, Coligen, et al., Ed. Wiley-Interscience,New York (1991) for example and radioactivity can be measured usingscintillation counting.

In one embodiment, a method of detecting Notch3 in a biological sample(e.g., tissue, blood, sera) or a prepared biological sample can comprisethe step of contacting an antibody of this invention with the sample andobserving the anti-Notch3 antibody bound to the Notch3 in the sample ordetermining the amount of the anti-Notch3 antibody bound to Notch3 inthe sample.

In another embodiment, a method of detecting Notch3 in a subjectcomprises the step of administering an antibody of this invention to thesubject and observing the anti-Notch3 antibody bound to the Notch3 inthe subject or determining the amount of the anti-Notch3 antibody boundto Notch3 in the subject (e.g., human, mouse, rabbit, rat, etc.).

One aspect of the invention is the detection and diagnosis of a diseaseor disorder associated with aberrant expression of Notch3 in an animal,preferably a mammal and most preferably a human. In one embodiment,diagnosis comprises: a) administering (for example, parenterally,subcutaneously, or intraperitoneally) to a subject an effective amountof a labeled molecule which specifically binds to Notch3; b) waiting fora time interval following the administration permitting the labeledmolecule to preferentially concentrate at sites in the subject where thepolypeptide is expressed (and for unbound labeled molecule to be clearedto background level); c) determining background level; and d) detectingthe labeled molecule in the subject, such that detection of labeledmolecule above the background level indicates that the subject has aparticular disease or disorder associated with aberrant expression ofNotch3. Background level can be determined by various methods including,comparing the amount of labeled molecule detected to a standard valuepreviously determined for a particular system.

It will be understood in the art that the size of the subject and theimaging system used will determine the quantity of imaging moiety neededto produce diagnostic images. In the case of a radioisotope moiety, fora human subject, the quantity of radioactivity injected will normallyrange from about 5 to 20 millicuries of ⁹⁹Tc. The labeled antibody orantibody fragment will then preferentially accumulate at the location ofcells which contain the specific protein. In vivo imaging is describedin Burchiel, et al., “Immunopharmacokinetics of Radiolabeled Antibodiesand Their Fragments.” Chapter 13 in Tumor Imaging: The RadiochemicalDetection of Cancer, Burchiel, et al., eds., Masson Publishing (1982).

Depending on several variables, including the type of label used and themode of administration, the time interval following the administrationfor permitting the labeled molecule to preferentially concentrate atsites in the subject and for unbound labeled molecule to be cleared tobackground level is 6 to 48 hours, 6 to 24 hours, or 6 to 12 hours. Inanother embodiment the time interval following administration is 5 to 20days or 5 to 10 days.

In an embodiment, monitoring of the disease or disorder is carried outby repeating the method for diagnosing the disease or disease, forexample, one month after initial diagnosis, six months after initialdiagnosis, one year after initial diagnosis, etc.

Presence of the labeled molecule can be detected in the patient usingmethods known in the art for in vivo scanning These methods depend uponthe type of label used. Skilled artisans will be able to determine theappropriate method for detecting a particular label. Methods and devicesthat may be used in the diagnostic methods of the invention include, butare not limited to, computed tomography (CT), whole body scan such asposition emission tomography (PET), magnetic resonance imaging (MRI),and sonography.

In a specific embodiment, the molecule is labeled with a radioisotopeand is detected in the patient using a radiation responsive surgicalinstrument (U.S. Pat. No. 5,441,050). In another embodiment, themolecule is labeled with a fluorescent compound and is detected in thepatient using a fluorescence responsive scanning instrument. In anotherembodiment, the molecule is labeled with a positron emitting metal andis detected in the patent using positron emission-tomography. In yetanother embodiment, the molecule is labeled with a paramagnetic labeland is detected in a patient using magnetic resonance imaging (MRI).

In another aspect, the present invention provides a method fordiagnosing the predisposition of a patient to develop diseases caused bythe unregulated expression of cytokines. Increased amounts of Notch3 incertain patient cells, tissues, or body fluids may indicate that thepatient is predisposed to certain diseases. In one embodiment, themethod comprises collecting a cell, tissue, or body fluid sample asubject known to have low or normal levels of Notch3, analyzing thetissue or body fluid for the presence of Notch3 in the tissue, andpredicting the predisposition of the patient to certain diseases basedupon the level of expression of Notch3 in the tissue or body fluid. Inanother embodiment, the method comprises collecting a cell, tissue, orbody fluid sample known to contain a defined level of Notch3 from apatient, analyzing the tissue or body fluid for the amount of Notch3,and predicting the predisposition of the patient to certain diseasesbased upon the change in the amount of Notch3 compared to a defined ortested level established for normal cell, tissue, or bodily fluid. Thedefined level of Notch3 may be a known amount based upon literaturevalues or may be determined in advance by measuring the amount in normalcell, tissue, or body fluids. Specifically, determination of Notch3levels in certain tissues or body fluids permits specific and early,preferably before disease occurs, detection of diseases in the patient.Diseases that can be diagnosed using the present method include, but arenot limited to, the diseases described herein. In the preferredembodiment, the tissue or body fluid is peripheral blood, peripheralblood leukocytes, biopsy tissues such as lung or skin biopsies, andtissue.

The antibody of the present invention can be provided in a kit, i.e.,packaged combination of reagents in predetermined amounts withinstructions for performing the diagnostic assay. Where the antibody islabeled with an enzyme, the kit may include substrates and cofactorsrequired by the enzyme (e.g., a substrate precursor which provides thedetectable chromophore or fluorophore). In addition, other additives maybe included, such as stabilizers, buffers (e.g., a block buffer or lysisbuffer), and the like. The relative amounts of the various reagents maybe varied widely to provide for concentrations in solution of thereagents which substantially optimize the sensitivity of the assay.Particularly, the reagents may be provided as dry powders, usuallylyophilized, including excipients which on dissolution will provide areagent solution having the appropriate concentration.

EXAMPLES

The following examples are offered by way of illustration and not by wayof limitation.

Example 1 Generation of Immunogen: Notch3 Extracellular Domain-Fc FusionProtein

Notch3 protein sequence was analyzed using an internet-based researchsoftware and service (Motif Search). The extracellular moiety of Notch3consists of 34 epithelial growth factor (EGF) repeats, three LIN12signature motifs, and a heterodimerization domain. The cDNAs coding forthe EGF repeat region (amino acid 43-1377) and LIN12/dimerization (LD)domain (amino acid 1378-1640) of Notch3 were synthesized by PCRamplification from human liver and pancreatic RNAs (Ambion, Inc. Austin,Tex.), respectively, followed by a first strand cDNA synthesis usingInvitrogen's Superscriptase III cDNA synthesis kit and protocol(Invitrogen, Carlsbad, Calif.). The PCR-synthesized Notch3-EGF repeatDNA fragment (˜4 kb) and Notch3-LD DNA fragment (˜0.8 kb) were clonedinto Tanox's internally generated expression vectors, His-γ1Fc/pSec andHis-γ1Fc/pCD3.1, which resulted two sets of expression plasmids, oneexpressing Notch3-EGF/Fc fusion protein and the other expressingNotch3-LD/Fc fusion protein. In both of the fusion proteins, a signalpeptide was linked to the N-terminus, and a human γ1Fc sequence wasfused to C-terminus of Notch3-EGF or Notch3-LD.

Expression of Notch3-EGF/Fc and Notch3-LD/Fc fusion proteins wasverified by transient transfection of the Notch3 expression plasmidsinto 293T (American Type Culture Collections (ATCC Number CRL-11268),Manassas, Va.) and Flip-in CHO cells (Invitrogen, Carlsbad, Calif.),respectively. Prior to transfection, cells were cultured in DMEM(Invitrogen, Carlsbad, Calif.) growth medium containing 10% fetal calfserum (FCS), 2 mM of glutamine, and 1× essential amino acid solution(Invitrogen, Carlsbad, Calif.), followed by seeding 3-5×10⁵ cells perwell in 6-well plate and growing for 24 hours. Three micrograms each ofthe Notch3 fusion protein expression plasmids were transfected into eachwell using Invitrogen's Lipofectamine 2000 transfection system(Invitrogen, Carlsbad, Calif.) following manufacturer's protocol. Aftertransfection, the cells were cultured in growth medium for 3-4 hours,then switched to DMEM medium containing 2% FCS and cultured for 60-66hours before drawing conditioned medium for secreted protein analysis.

For stable cell line generation, each of the fusion protein containingplasmids, Notch3-EGF/Fc (His-Fcγ/pSec backbone vector) and Notch3-LD/Fc(within His-Fcγ/pSec), were cotransfected with pOG-44 (Invitrogen,Carlsbad, Calif.) into Flip-in CHO cells. After transfection, the cellswere cultured in DMEM growth medium overnight, followed by a transferinto growth medium containing 800 μg/ml hygromycin and then cultured forat least two weeks until the cells not carrying Notch3 expressionplasmid DNA were eliminated by antibiotics. Cells exhibiting hygromycinresistance were established as stable cells lines for further testing.

Transient and stable cell lines were subjected to Western blot analysisto verify the expression and secretion of Notch3-EGF/Fc or Notch3-LD/Fcfusion protein. Transfected cells were harvested from culture dishes,washed once with phosphate buffered saline (PBS), resuspended indeionized water, followed by adding an equal volume of 2× protein sampleloading buffer (BioRad, Hercules, Calif.), heating at 100° C. for 10minutes, and loading on an SDS-PAGE gel. In addition, secreted proteinfrom the medium was also analyzed by mixing an equal volume ofconditioned medium with 2× protein sample loading buffer, heating at100° C. for 10 minutes, and loading on an SDS-PAGE gel. The samples wereseparated by electrophoresis in a 4-15% gradient SDS-PAGE (BioRad,Hercules, Calif.). The proteins were transferred from the gel to a PVDFmembrane (BioRad, Hercules, Calif.). Non-specific binding sites wereblocked using 5% non-fat dry milk in PBST (PBS with 0.05% tween-20) forat least one hour. The presence of Notch3-EGF/Fc and/or Notch3-LD/Fcfusion proteins was detected by incubation with γFc-specific,HRP-conjugated antibody (Sigma, St Louis, Mo.) in blocking buffer forone hour at room temperature. The membrane was washed three times inPBST and developed with Supersignal Chemiluminescent Substrate (Pierce,Rockford, Ill.) according to the manufacturer's protocol.

After verifying that the fusion proteins were expressed and exhibitedthe correct banding pattern on Western blots, Notch3/Fc fusion proteinwas generated for purification. The stable cell line generated asdescribed above was cultured in DMEM with 2% FCS for up to 5 days. Oneliter of conditioned medium was collected and subjected to protein-Aaffinity binding. The column was washed with PBS and the bound proteinswere eluted in 50 mM citrate buffer (pH2.8). The pH was then brought toneutral by adding 1 M Tris-HCl buffer (pH8). The purified protein wasanalyzed by protein gel analysis using 4-15% gradient SDS-PAGE. Theprotein concentration was assayed using Coomassie blue reagent followingthe manufacturer's protocol (Pierce, Rockford, Ill.). Through thisprocedure, milligram quantities of Notch3-EGF/Fc and Notch3-LD/Fcprotein were purified for immunization and ELISA binding assays.

Example 2 Generation of Anti-Notch3 Mabs

Male A/J mice (Harlan, Houston, Tex.), 8-12 week old, were injectedsubcutaneously with 25 μg of Notch3-EGF/Fc or Notch3-LD/Fc in completeFreund's adjuvant (Difco Laboratories, Detroit, Mich.) in 200 μl of PBS.At two-week intervals, the mice were twice injected subcutaneously with25 μg of Notch3-EGF/Fc or Notch3-LD/Fc in incomplete Freund's adjuvant,respectively. Two weeks after the injections and three days prior tosacrifice, the mice were again injected intraperitoneally with 25 μg ofthe same antigen in PBS. For each fusion, single cell suspensions wereprepared from spleen of an immunized mouse and used for fusion withSp2/0 myeloma cells; 5×10⁸ of Sp2/0 and 5×10⁸ of spleen cells were fusedin a medium containing 50% polyethylene glycol (M.W. 1450) (Kodak,Rochester, N.Y.) and 5% dimethylsulfoxide (Sigma, St. Louis, Mo.). Thecells were then adjusted to a concentration of 1.5×10⁵ spleen cells per200 μl of the suspension in Iscove medium (Invitrogen, Carlsbad,Calif.), supplemented with 10% fetal bovine serum, 100 units/ml ofpenicillin, 100 μg/ml of streptomycin, 0.1 μM hypoxanthine, 0.4 μMaminopterin, and 16 μM thymidine. Two hundred microliters of the cellsuspension were added to each well of about sixty 96-well plates. Afterabout ten days, culture supernatants were withdrawn for screening theirantibody-binding activity using ELISA.

The 96-well flat bottom Immulon II microtest plates (Dynatech,Laboratories, Chantilly, Va.) were coated using 100 μl of Notch3-EGF/Fcor Notch3-LD/Fc (0.1 μg/ml) in phosphate buffered saline (PBS)containing 1×Phenol Red and 3-4 drops pHix/liter (Pierce, Rockford,Ill.) and incubated overnight at room temperature. After the coatingsolution was removed by flicking of the plate, 200 μA of blocking buffercontaining 2% BSA in PBST (1×PBS with 0.05% Tween-20 and 0.1%merthiolate) was added to each well for one hour to block non-specificbinding. The wells were then washed with PBST (PBS with 0.05% Tween-20).Fifty microliters of culture supernatant from each fusion well wascollected and mixed with 50 μl of blocking buffer and then added to theindividual wells of the microtiter plates. After one hour of incubation,the wells were washed with PBST. The bound murine antibodies were thendetected by reaction with horseradish peroxidase (HRP)-conjugated,Fc-specific goat anti-mouse IgG (Jackson ImmunoResearch Laboratories,West Grove, Pa.). HRP substrate solution containing 0.1%3,3,5,5-tetramethyl benzidine and 0.0003% hydrogen peroxide (Sigma, St.Louis, Mo.) was added to the wells for color development for 30 minutes.The reaction was terminated by the addition of 50 ml of 2 M H₂SO₄, perwell. The OD at 450 nm was read with an ELISA plate reader (MolecularDevices, Sunnyvale, Calif.). The ELISA using supernatant from the threehybridoma clones producing mAbs 255A-71, 255A-77, and 256A-13 showedstrong binding activity to the purified Notch3/FC fusion protein towhich it was generated (Table 1).

TABLE 1 ELISA OD readings of anti-Notch3 Mabs using hybridomasupernatant ELISA coating protein Notch3-EGF/Fc Notch3-EGF/FcNotch3-LD/Fc Hybridoma supernatant Control 255A-71 Control 255A-77Control 256A-13 Mean 0.010 2.225 0.019 1.717 0.019 2.828 S.D. 0.0030.064 0.003 0.059 0.002 0.047

Note: Controls were hybridoma clones without specific binding activityto Notch3.

The positive hybridoma clones from this primary ELISA screening werefurther isolated by single colony-picking and a second ELISA assay asdescribed above was done to verify specific binding to the chosenimmunogen. The confirmed hybridoma clones were expanded in larger scalecultures. The monoclonal antibodies (mAbs) were purified from the mediumof these large scale cultures using a protein A affinity column. Theanti-Notch3 mAbs were then characterized using cell-based bindingassays, microscopy, Western blot, and FACS analysis.

Example 3 Cell-Based Binding Assays for Anti-Notch3 Mabs

The cell-based binding assays used to characterize the anti-Notch 3 mAbsrequired cloning a full-length of human Notch3 open reading frame into avector, in this case pcDNA3.1/Hygro (Invitrogen, Carlsbad, Calif.). TheNotch3-coding region was synthesized by RT-PCR using human liver tumorRNA (Ambion, Inc., Austin, Tex.) as a template. The final plasmidconstruct, Notch3/Hygro, expressed a full-length Notch3 protein asdepicted in FIG. 1. A stable cell line expressing Notch3 was generatedby transfecting the plasmid construct into 293T cells using aLipofectamine 2000 kit following the same procedure as described inExample 1. Well-isolated single colonies were picked up and grown inseparate wells until enough clonal cells were amplified. Stable 293Tclones that were resistant to hygromycin and expressed high levels ofNotch3 protein were identified by Western blot analysis and byfluorescent electromicroscopy using polyclonal anti-Notch3 antibodies(R&D Systems, Minneapolis, Minn.).

A Notch3 expression plasmid comprising only the Notch LIN12/dimerization(LD) domain and the transmembrane (TM) domain was also constructed byPCR and subcloning into pcDNA3.1 (Invitrogen, Carlsbad, Calif.). Thisplasmid construct also contains a V5 tag at its C-terminus and wastermed Notch3-LDTM/V5. A stable cell line expressing this plasmid wasgenerated according to the procedure described in Example 1.

Human Sup-T1 cell line (ATCC CRL-1942), which naturally expressesNotch3, was used as a control in the FACS analysis. This cell line'sNotch 3 expression was confirmed by Western blot analysis. Sup-T1 cellswere cultured in RPMI1640 media containing 10% fetal calf serum, 2 mM ofglutamine and 1× essential amino acid solution (Invitrogen, Carlsbad,Calif.) and Western blot was performed as described in Example 1.

Cell-based antibody-binding was assessed using FMAT™ 8100 HTS System(Applied Biosystems, Foster City, Calif.) and protocol provided by themanufacturer with some modification. Cell lines expressing Notch3 wereseeded in 96-well plates at a density of 30,000-50,000 cells per well.After 20-24 hours, anti-Notch3 mAbs and 1×PBS reaction buffer were addedto the wells and incubated for one hour at 37° C. Cy-5-conjugatedanti-mouse IgG antibody was added to the wells after removal of primaryantibodies. The fluorescent intensity of bound antibody was measured byFMAT™ 8100 HTS System.

Cell-based antibody-binding was also assessed by fluorescence-activatedcell sorter (FACS). Cells were first incubated with anti-Notch3 mAbs in1×PBS. After three washes, the cells were incubated with fluorescentmolecule-conjugated secondary antibody. The cells were resuspended,fixed in 1×PBS with 0.1% paraformaldehyde, and analyzed by FACS machine(BD Sciences, Palo Alto, Calif.). Cell-based FMAT (fluorescencemacro-confocal high-throughput screening) assay and FACS analysisconfirmed that all three mAbs 255A-71, 255A-77, and 256A-13 indeed bindto the Notch3 receptor expressed either from recombinant plasmidconstructs or as native protein in cultured cells (Table 2 and Table 3).

TABLE 2 Summary of anti-Notch3 mAbs binding activity in cell-based FMATassay 255A-71 255A-77 256-13 Notch3 (full-length) good good weakNotch3-LDTM no binding no binding good

TABLE 3 Mean fluorescence intensity of FACS analysis usingNotch3/Hygromycin- transiently transfected 293T and Sup-T1 cells ControlIgG1 255A-71 255A-77 256A-13 Notch3/Hyg 24.16 124.06 242.3 32.2 Sup-T124.51 58.16 70.53 55.44

Two of the anti-Notch3 mAbs, 255A-71 and 255A-77, generated fromNotch3-EGF/Fc specifically bind to the Notch3-EGF repeat region. Thethird mAb, 256A-13, generated from Notch3-LD/Fc specifically binds toNotch3-LD domain (Table 2 and 4).

Transiently transfected 293T cells with Notch3/Hygro plasmid were alsostained with immunofluorescence as described above and observed byfluorescent microscopy.

Example 4 Western Blot Analysis of Anti-Notch3 mAbs Binding Activity

Western blot was performed to assess anti-Notch3 mAbs binding activityto Notch3 under denaturing condition. For this purpose, purifiedNotch3-EGF/Fc and Notch3-LD/Fc fusion proteins were combined withprotein loading buffer (BioRad, Hercules, Calif.). Protein samples werealso prepared from the transiently or stably transfected cells describedin Example 1, which were harvested from culture dishes, washed once withphosphate buffered saline (PBS), resuspended in deionized water, andheated at 100° C. for 10 minutes after adding equal volume of 2× proteinsample loading buffer (BioRad, Hercules, Calif.). All samples wereseparated by electrophoresis in a 4-15% gradient SDS-PAGE (BioRad,Hercules, Calif.). The proteins were transferred from gel to PVDFmembrane (BioRad, Hercules, Calif.) and anti-Notch3 mAbs were applied tothe Western blot membrane as the primary detection antibody. AnHRP-conjugated secondary antibody was used for detection and the signalgenerated using a Supersignal Chemiluminescent Substrate (Pierce,Rockford, Ill.) as described above.

Western blot analysis under denatured condition showed that mAb 256A-13has strong binding activity for denatured Notch3 protein. mAb 255A-71also binds to denatured Notch3 protein with lower affinity, while mAb255A-77 does not bind to the denatured protein (Table 4).

TABLE 4 Summary of Western blot band intensity using anti-Notch3 Mabs255A-71 255A-77 256-13 Notch3-EGF/Fc weak no binding no bindingNotch3-LD/Fc no binding no binding strong Notch3 (full-length) weak nobinding strong

Example 5 Sequencing of Anti-Notch3 mAbs

Before sequencing the anti-Notch3 mAbs, the antibody IgG subtype wasdetermined using Isostrip Mouse Monoclonal Antibody kit (RocheDiagnositcs, Indianapolis, Ind.). The results showed that all threemAbs, 255A-71, 255A-77 and 256A-13, comprised of an IgG₁ heavy chain andkappa light chain.

The variable region sequences of heavy chain and light chain weredecoded through RT-PCR and cDNA cloning. Total RNAs from each hybridomaclone of mAbs 255A-71, 255A-77 and 256A-13 were isolated using RNeasyMini kit and following manufacturer's protocol (Qiagen Sciences,Valencia, Calif.). First strand cDNA was synthesized using the RNAtemplate and Superscriptase III kit (Invitrogen, Carlsbad, Calif.). Thevariable region of light chain and heavy chain cDNAs were PCR-amplified(High Fidelity PCR System, Roche) from first strand cDNA usingdegenerative forward primers covering the 5′-end of mouse kappa chaincoding region and a reverse primer matching the constant region atjuncture to the 3′-end of variable region, or using degenerative forwardprimers covering the 5′-end of mouse heavy chain coding region and aconstant region reverse primer in mouse heavy chain. The PCR product wascloned into pCRII-TOPO following manufacturer's protocol (Invitrogen,Carlsbad, Calif.), and sequenced by Lone Star Lab (Houston, Tex.). Thenucleotide sequences were analyzed utilizing computer software programDNAStar (DNASTAR, Inc., Madison, Wis.). Each of the anti-Notch3 mAbsequences was determined by sequences from multiple PCR clones derivedfrom same hybridoma clone.

The variable heavy chain region of MAb 255A-71 contains 123 amino acidresidues and the light chain variable region contains 116 amino acidresidues (FIGS. 2A and 2B). The variable heavy chain region of mAb255A-77 contains 120 amino acid residues and the light chain variableregion contains 123 amino acid residues (FIGS. 3A and 3B). The variableheavy chain region of mAb 256A-13 contains 121 amino acid residues andthe light chain variable region contains 102 amino acid residues (FIGS.4A and 4B).

Example 6 Detection Using Anti-Notch3 mAbs

A. Biopsy Sample Fixation and Slide Preparation

Tumor or tissue samples are removed from a subject suspected of having aNotch 3 related disorder or disease. The sample is placed in cold PBS.The samples are washed with PBS to remove any blood or other substances,and then cut to the proper size, generally thinner than 3 mm for betterfixation. The sample is placed in a fixative, such as 4%paraformaldehyde or 10% buffered formalin, and allowed to fix at 4° C.for 10-15 minutes or one hour in a rotating plate. The samples arechanged to fresh fixative and incubated at 4° C. for overnight.

The fixed samples are washed once with PBS for 1 minute, followed bythree 20-minute-washes with PBS. The samples are then seriallydehydrated as follows: 30% ethanol [volume/volume in ddH2O (distilleddeionized water)] for 1 hour, 50% ethanol for 1 hour, 70% ethanolovernight or over a weekend, 95% ethanol for 3 hour or overnight fortwice, and finally two 1-hour dehydration in 100% ethanol. The samplesmay be stored at −20° C. For slide preparation, the samples areincubated three times in 100% ethanol at room temperature, each for onehour. Then, the samples are incubated two times in xylene each for 30-40minutes, and three times in paraffin each for 40 minutes. Finally, thesamples are embedded for cutting and slide-amounting. The slides may bestored at 4° C.

B. Immunohistochemical Staining

To prepare slides for immunostaining, slide tissue sections aredeparaffinized twice in Xylene each for 20 minutes, and rehydrated bysoaking in 100%, 95% ethanol and ddH2O each for 2 minutes. The slidesmay be kept in ddH2O prior to immunostaining Alternatively, antigenretrieval is performed to enhance immunostaining A glass beaker filledwith 1000 ml ddH2O is heated on a hotplate to 95-99° C. or 102-104° C.The slides from above are soaked in antigen-retrieval buffer, 1X BullsEye solution (BioCare) in a slide container jar, which is immediatelyplaced in the hot water beaker, heated for 20 minutes and subsequentlywashed with ddH2O 2-3 times.

For immunostaining, the slides are washed twice in PBS each for 3minutes, and incubated in PBS containing 3% hydrogen peroxidase for 15minutes to block the endogenous peroxidase. The slides are then washedthree times in PBST (PBS with 0.1% Tween®-20) for 2 minutes per wash.Non-specific proteins are blocked by incubating with 10% normal serum in0.5% PBST (0.5% Tween®-20 in PBS) for 30-60 minutes at room temperature.The slides are incubated with anti-Notch3 antibody (the first antibody)in 5% normal goat serum in 0.1% PBST overnight at 4° C., followed by sixwashes with PBST each for 5 minutes. Then, the slides are incubated with1:200 biotinylated 2nd antibody (detection antibody) for 1 hour at roomtemperature and are washed six times with PBST each for 5 minutes.Slides are incubated in 1/50 ABC/PBS buffer for 45-60 minutes, followedby four 5-minute washes in PBST and two 5-minute-washes in 0.1M Tris, pH7.5/0.3M NaCl. To develop the color, DAB solution (one DAB tablet in 5ml ddH2O, Sigma reagent and protocol) is added to the slides for 2-10minutes and the slides are washed several times with ddH2O. The slidesare counterstained with Hematoxylin for 1 minute, washed, dehydrated,and mounted with mounting medium and cover slide. The Notch3 positivestaining may be observed by microscopy, and quantified by manual orautomatic microscopic instrument.

Example 7 Examining Soluble Notch3 in Serum by ELISA

Blood samples are collected from a subject and stored in tubes at 4° C.Serum is taken from top layer after precipitation of blood cells andused to examine soluble Notch3 by ELISA described as follows. The96-well ELISA plate is coated with capture antibody, i.e., anti-Notch3antibody, which is diluted to 1-4 μg/ml in PBS and distributed at 50 μlper well. The plate is sealed and incubated overnight at 4° C. Afterbringing the plate to room temperature, the capture antibody solution isremoved and non-specific binding is blocked by adding 200 μl of blockingbuffer containing 10% fetal bovine serum (FBS), 10% newborn calf serum(NBCS), or 1% BSA (immunoassay grade) in PBS, and incubated at roomtemperature for 1-2 hours. The plate is then washed at least three timeswith PBST (0.5% Tween®-20 in PBS).

The serum samples are serially diluted in blocking buffer with 0.5%TWEEN®-20, and 100 μl of the diluted samples are added to each well. Theplate is sealed and incubated for 2-4 hours at room temperature orovernight at 4° C. The plates are washed with PBST. For detection, asecondary antibody that recognizes the different epitope of Notch 3 thanthe capture antibody is used. This second antibody is labeled with, forexample, horseradish peroxidase (HRP) and added to each well at aconcentration of about 0.1-1 ug/ml. The plate is sealed and incubated atroom temperature for 30 minutes. The wells are washed at least 5 timeswith PBST. Color development solution is prepared by dissolving 150 mg2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid (Sigma) in 500 mlof 0.1 M citric acid, pH 4.35 (Fisher), and 100 μA is dispensed intoeach well. The plate is incubated at room temperature for 5-80 minutesfor color development. The optical density (OD) is read with amicroplate reader setting at 405.

Example 8 Detecting Circulating Cancer Cells (CTC) by Anti-Notch3Antibody Staining

CTCs are indicative of cancer metastasis, which occur when cells shedfrom the invasive primary tumor enter the circulation and begin to growin distant locations in the body. Using targeted antibodies againstspecific markers on the tumor cells, CTCs are detected from theperipheral blood of patients, which has been linked to diseaseprogression.

A. Enrichment of Circulating Tumor Cells from the Blood by GradientCentrifugation

Blood samples are drawn from a subject and stored in 4° C. forprocessing within 24 hours using, for example, OncoQuick densitygradient system (Greiner Bio-One GmbH, Frickenhausen, Germany).OncoQuick is a separation device composed of a centrifugation tube witha liquid density separation medium and a porous barrier membraneoptimized for the enrichment of circulating tumor cells from blood. Theblood is layered on top of the gradient, and centrifuged for 20 minuteswith 1,600×g at 4° C. The complete supernatant above the porous barrieris transferred into a new tube pretreated with the washing bufferdelivered with the OncoQuick device and cells are washed twice with 50ml of washing buffer by centrifugation at 200×g at 4° C. for 5 minutes.After the second washing step, the cells are resuspended in 1 ml washingbuffer, counted in a Neubauer chamber, and centrifuged at 110×g for 3minutes using a cytocentrifuge (Hettich model 16 A, Tuttlingen, Germany)on adhesive slides (Superfrost Plus, Menzel Glassware, Braunschweig,Germany) at a concentration of 5×10⁵ cells per area of 240 mm² or anequal cellular density of a smaller area when less cells were retrievedfrom the gradient. Cytospin slides were air-dried overnight and storedat −80° C. until staining.

B. Immunocytochemical Staining for the Identification of CirculatingTumor Cells in the Blood

Slides are fixed according to the manufacturer's instructions withSolution B of the Epimet Kit (Micromet, Martinsried, Germany) containingformaldehyde. After blocking with a serum-free blocking reagent (Dako)for 20 minutes, the slides are incubated with fluorochrome (such as Cy3)conjugated anti-Notch3 antibody and simultaneously counterstained withanti-CD45 antibody labeled with FITC at a dilution of 1/50 to 1/200 for45 minutes. Finally, the slides are incubated for 1 minute with4′,6-diamidino-2-phenylindole (Sigma, Deisenhofen, Germany), mountedwith 0.9% (w/v) NaCl and covered with coverslips. Cells are classifiedas circulating tumor cells when staining was positive for Notch3,negative for CD45, and when morphologic criteria were fulfilled.

Example 9 Detecting Disseminated Tumor Cells in Bone Marrow

Bone marrow is aspirated directly after surgery under general anesthesiafrom both iliac crests, and screened for the presence of Notch3-positivecells. In brief, 2×10⁶ mononuclear cells of each bone marrow specimenare analyzed. The anti-Notch3 antibody is used at a concentration of 1-5μg/ml to detect tumor cells in the cytospin preparation method describedabove. A negative staining control is obtained by using an unrelatedmouse-myeloma IgG1 antibody (MOPC 21, Sigma) at 1-5 μg/ml. The Sup T1T-cell line described above in Example 3 may serve as a positive controlfor Notch3 immunostaining in each staining batch. The specific reactionof the primary antibody is developed with the alkaline phosphataseanti-alkaline phosphatase technique (Dako), combined with the fuchsinstaining, to indicate antibody binding as described before. Cytospinslides are analyzed with an automated cellular imaging system, such asChromaVision Medical Systems, Inc., San Juan Capistrano, Calif.

Those skilled in the art will recognize, or be able to ascertain usingno more than routine experimentation, many equivalents to the specificembodiments of the invention described herein. Such equivalents areintended to be encompassed by the following claims.

1. An isolated antibody comprising a variable light (VL) chain regioncomprising the amino acid sequence of SEQ ID NO: 3, wherein the antibodybinds specifically to Notch3.
 2. An isolated antibody comprising avariable heavy (VH) chain region comprising the amino acid sequence ofSEQ ID NO: 2, wherein the antibody binds specifically to Notch3.
 3. Theantibody of claim 1, further comprising a variable heavy (VH) chainregion comprising the amino acid sequence of SEQ ID NO:
 2. 4. Anisolated antibody comprising a variable heavy (VH) chain regioncomprising complementarity determining regions (CDRs) of SEQ ID NO: 8,9, and 10, wherein the antibody binds specifically to Notch3.
 5. Anisolated antibody comprising a variable light (VL) chain regioncomprising complementarity determining regions (CDRs) of SEQ ID NO: 11,12, and 13, wherein the antibody binds specifically to Notch3.
 6. Theantibody of claim 4, further comprising a variable light (VL) chainregion comprising CDRs of SEQ ID NO: 11, 12, and
 13. 7. The antibody ofany of claims 1-6, wherein the antibody is an antibody fragment.
 8. Theantibody of claim 7, wherein the antibody is a single chain Fv.
 9. Theantibody of any of claims 1-6, further comprising a label.
 10. Anisolated antibody that binds specifically to the EGF repeat region fromamino acid residue 43 to 1377 of human Notch3.
 11. The antibody of claim10, wherein the antibody binds to native Notch3 protein.
 12. Theantibody of claim 11, wherein the antibody binds to denatured Notch3protein.
 13. The antibody of any of claims 10-12, further comprising alabel.
 14. The antibody of any of claims 10-12, wherein the antibody isan antibody fragment.
 15. The antibody of claim 14, wherein the antibodyis a single chain Fv.
 16. The antibody of claim 14, further comprising alabel.